Glycosylated Hemoglobin Test
(HbA1c; GHb; Glycohemoglobin; Diabetic Control Index)
A glycosylated hemoglobin test (HbA1c) is a blood test that measures the amount of glycosylated hemoglobin in the blood. Hemoglobin is a protein found in the blood. Glycosylated hemoglobin means that glucose (sugar) has attached to the hemoglobin protein. The higher your blood sugar is, the more that glucose gets attached to your hemoglobin.
Reasons for Test
HbA1c shows how high your blood sugar levels have been during the past three months. This can help your doctor determine how well you are controlling your diabetes. Your doctor may also use HbA1c to test you for diabetes.
There are no major complications associated with this test.
What to Expect
Description of Test
You will be asked to sit. An area inside your elbow will be cleaned with an antiseptic wipe. A large band will be tied around your arm. The needle will then be inserted into a vein. A tube will collect the blood from the needle. The band on your arm will be removed. After all the blood is collected, the needle will be removed. Some gauze will be placed over the site to help stop bleeding. You may also be given a bandage to place over the site. The process takes about 5-10 minutes.
Call Your Doctor
After the test, call your doctor if any of the following occurs:
- Persistent bleeding or discharge
In case of an emergency, call for emergency medical services right away.
American Diabetes Association
National Diabetes Education Program
Canadian Diabetes Association
American Diabetes Association. Standards of medical care in diabetes—2008. Diabetes Care. 2008;31:S12-S54.
Aronow WS, Ahn C, Weiss MB, Babu S. Relation of increased hemoglobin A1c levels to severity of peripheral arterial disease in patients with diabetes mellitus. Am J Cardiol. 2007;99:1468-1469.
Check your hemoglobin A1c IQ. National Diabetes Education Program website. Available at: http://nfb.org/Images/nfb/Publications/vodold/vspr9905.htm. Accessed September 29, 2014.
A new number. American Diabetes Association website. Available at: http://forecast.diabetes.org/magazine/features/new-number. Published November 2008. Accessed September 29, 2014.
Pradhan AD, Rifai N, Buring JE, Ridker PM. Hemoglobin A1c predicts diabetes but not cardiovascular disease in nondiabetic women. Am J Med. 2007;120:720-727.
Saudek CD, Herman WH, Sacks DB, et al. A new look at screening and diagnosing diabetes mellitus. J Clin Endocrinol Metab. 2008;93:2447-2453.
American Diabetes Association. Standards of medical care in diabetes mellitus. Diabetes Care. 21003 Jan;26 Suppl 1:s33-50. Available at: http://care.diabetesjournals.org/content/26/suppl_1/s33.full. Accessed September 29, 2014.
Last reviewed August 2014 by Kim Carmichael, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.